This invention relates to protection from shock and vibration, and in particular, to apparatus for protection of objects from damage resulting from seismic activity such as earthquakes. The invention is of particular significance to the protection of art objects and antiquities of museum quality and to the protection of display cabinets and contents; however, the invention is also applicable to protection of other objects such as scientific and medical instruments and other sensitive equipment, emergency equipment of all kinds, computers and computer files, housings and enclosures, floors and even entire buildings.
A wide variety of configurations have been utilized in the past for protection from damage due to earthquake. In one approach, the structure is designed to be exceedingly strong so that the structure and its support, such as a single object or an entire building, moves with the earth movement without damage. Another approach has been to support the object on some type of apparatus so that the object remains essentially fixed while the earth moves, with the object ultimately being restored to its original relationship with the earth. Structures of this general nature are shown in U.S. Pat. No. 4,496,130 and Italian Pat. No. 639,666. In one arrangement, a bowl and caster configuration is utilized to permit relative motion, with gravity or a spring providing the restoring force. Another approach utilizes a plurality of springs for suspending the object, with the springs providing isolation between the object and the earth movement.
Another approach has been to utilize cables and springs for controlling motion, and typical structures are shown in U.S. Pat. Nos. 4,371,143; 4,402,483; 4,565,039; 4,577,826, 4,617,769; and 4,662,133. While these designs have been satisfactory for some situations, problems are encountered in other arrangements and it is an object of the present invention to provide a new and improved isolator construction.